Factory reset and installation fail Steel HR

I've always had great success with my Steel HR and no problems with syncing etc. Until this week and, long story short, ended up needing to factory reset.

Big mistake. I went to my app (where my Scales are still connected) and clicked on "install a device". Everything was going fine, my device was recognised and connected ok. When clicking "next", I was taken to a screen asking me to create an account (despite starting the process from my already-set-up app). I typed in my email address, and was told the account already exists (correct) and so I clicked "login". At which point, I was taken straight back to the "devices" section of my app, with my Steel HR not installed. I tried again, and the exact same thing happened. Just a perpetual cycle of NEARLY installing my watch! Has anybody else experienced this? Thanks